Graded pore structure perovskite catalytic material and preparation method thereof

Abstract

The invention discloses a hierarchical pore structure perovskite catalytic material and a preparation method thereof, and belongs to the technical field of catalysts. The general chemical formula of the perovskite catalytic material with the hierarchical pore structure is La1-xCaxMnO3, x is more than or equal to 0.1 and less than or equal to 0.3, and two pore structures of macropores and mesopores exist in the catalytic material. The invention also discloses a preparation method of the perovskite catalytic material with the grade pore structure, which comprises the following steps: preparing a self-assembled ordered silicon dioxide microsphere template material, preparing a precursor solution, adding a surfactant and citric acid to prepare a mixed solution, dipping the self-assembled ordered silicon dioxide microsphere template material in the mixed solution, and drying to obtain the perovskite catalytic material with the grade pore structure. And calcining the solid mixture and etching with an alkaline solution. By adopting the perovskite catalytic material with the grade pore structure and the preparation method of the perovskite catalytic material, the problems of high cost and poor catalytic performance of the existing catalyst can be solved.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and in particular to a hierarchical pore structure perovskite catalytic material and a preparation method thereof. Background Art

[0002] With the growth of my country's economy and the acceleration of industrialization, environmental pollution and energy shortage problems are becoming increasingly serious, especially the greenhouse effect has caused great harm to human society and the natural environment. Industrial waste gas, mine gas, coalbed methane and natural gas vehicle exhaust all contain a large amount of methane. Methane is a potent greenhouse gas, and its greenhouse effect is 21 times that of carbon dioxide. Excessive content will aggravate global warming and increase the frequency and intensity of extreme weather events. At the same time, methane will participate in photochemical reactions in the atmosphere to produce ozone, which in turn causes or aggravates respiratory and cardiovascular diseases. Although methane is a greenhouse gas, as the main component of natural gas, it is also an important material resource and is widely used in home heating, industrial power generation and other fields. Methane is also an important raw material for the production of a variety of chemicals, such as methanol, ammonia and ethylene. However, as the most stable hydrocarbon molecule, methane is difficult to activate and oxidize. Its traditional combustion temperature is usually higher than 1400°C, and the combustion process produces NO x , CO and other secondary pollutants.

[0003] The development of catalytic combustion technology has made it possible to efficiently utilize methane at lower temperatures, which not only avoids the energy loss caused by high-temperature combustion, but also reduces the generation of harmful by-products. At present, catalytic combustion technology has been applied in many aspects of industrial production and daily life. In order to achieve efficient utilization of methane, it is particularly important to develop high-performance catalysts. Precious metals such as palladium, platinum and rhodium have become the mainstream catalysts for methane utilization at this stage due to their excellent catalytic activity. However, these precious metals are expensive, scarce in resources, and prone to agglomeration, sintering and heat loss under high temperature conditions. Perovskite catalysts are expected to become a substitute for precious metal catalysts due to their unique chemical flexibility, structural thermal stability, excellent electron mobility and simple preparation methods.

[0004] Perovskite catalysts have been widely used in the field of catalytic combustion due to their excellent catalytic activity and environmental friendliness. Existing patent 202210805553.9 Indium-based perovskite catalyst LaInO 3 A method for preparing indium-based perovskite and its application in electrochemical reduction of CO 2 The perovskite has high catalytic selectivity and high current density. Patent 202211140422.X LaAl designed in the application of aluminum-doped lanthanum-manganese perovskite catalyst 1-x Mn x O 3The series of perovskites can effectively degrade organic matter and improve water quality in a wide pH range. Patent 201510304459.5LaNiO 3 The preparation method of perovskite composite catalyst and its application method are simple and easy to implement, and have significant catalytic effect on high-pressure liquefaction of biomass. Although perovskite catalysts have many advantages mentioned above, perovskite materials prepared by traditional sol-gel method, coprecipitation method and hydrothermal synthesis method usually have low specific surface area and limited pore structure, which limits the number of catalytic active sites on the surface and significantly affects the overall catalytic performance and service life of the material. Summary of the invention

[0005] The purpose of the present invention is to provide a hierarchical pore structure perovskite catalytic material and a preparation method thereof, so as to solve the problems of high cost and poor catalytic performance of existing catalysts.

[0006] To achieve the above-mentioned purpose, the present invention provides a hierarchical pore structure perovskite catalytic material, the chemical formula of which is La (1-x) Ca x MnO 3 , where 0.1≤x≤0.3, there are two types of pore structures in the catalytic material: macropores and mesopores.

[0007] The method for preparing the hierarchical pore structure perovskite catalytic material comprises the following steps:

[0008] S1. Prepare two solutions A and B, wherein solution A is an ethanol solution of ammonia water and solution B is an ethanol solution of tetraethyl orthosilicate;

[0009] S2, mixing solution A and solution B, stirring evenly at room temperature, and then heating and stirring to obtain a suspension;

[0010] S3. Centrifuge the suspension to obtain a white precipitate. The centrifugal speed is 1000 rpm to 2000 rpm, and the centrifugal time is 20 min to 50 min. The centrifugal speed is preferably 2000 rpm, and the centrifugal time is preferably 30 min.

[0011] S4, washing the white precipitate with a deionized water solution of ethanol until the pH is neutral; drying to obtain a silica microsphere material, the drying temperature is 30°C to 80°C, and the drying time is 8h to 24h; the drying temperature is preferably 50°C, and the drying time is preferably 12h;

[0012] S5, adding silica microspheres into an ethanol solution, and obtaining a self-assembled ordered silica microsphere template material after ultrasonication, centrifugation, filtration and drying;

[0013] S6. Weigh lanthanum nitrate, manganese nitrate, and doped metal salt and dissolve them in deionized water to prepare a precursor solution;

[0014] S7, adding a surfactant and citric acid to the precursor solution, stirring evenly at room temperature to obtain a mixed solution;

[0015] S8, adding the self-assembled ordered silica microsphere template to the mixed solution of S7, fully impregnating, vacuum filtering, and drying in a forced air drying oven to obtain a solid mixture;

[0016] S9, placing the solid mixture into a muffle furnace for calcination, and cooling to room temperature; etching with an etching solution at 60°C to 90°C to obtain a coarse-grade porous perovskite material; the etching solution temperature is preferably 80°C.

[0017] S10, washing the coarse-grade pore perovskite material with deionized water until it becomes neutral, and obtaining the fine-grade pore perovskite material after drying.

[0018] Preferably, in S1, the volume ratio of ammonia water to ethanol in solution A is 1:3-5, preferably 1:4. The volume ratio of tetraethyl orthosilicate to ethanol in solution B is 1:6-9, preferably 1:8.

[0019] Preferably, in S2, the heating temperature for heating and stirring is 50°C to 70°C; and the stirring time is 3h to 4h, preferably 4h.

[0020] Preferably, in S5, the mass ratio of silica microspheres to ethanol solution is 1:40-60, the ultrasonic oscillation time is 0.5h-2h, the centrifugal speed is 2000rpm-3000rpm, the centrifugal time is 8h-16h, and the drying is carried out at room temperature for 24h-72h.

[0021] Preferably, in S6, the doped metal salt is one of strontium nitrate, calcium nitrate, potassium nitrate and cerium nitrate, and the molar ratio of lanthanum nitrate, manganese nitrate and the doped metal salt is 3-5:4-6:1, preferably 4:5:1.

[0022] Preferably, in S7, the surfactant is a mixture of one or more of ethylene glycol, polyethylene glycol, and block polyether, the mass ratio of the surfactant to citric acid is 1:2-4, and the stirring time at room temperature is 3h-6h.

[0023] Preferably, in S8, the immersion time is 10h to 20h, a hydrophilic polytetrafluoroethylene microporous filter membrane with a pore size of 0.45um is used for suction filtration, the drying temperature is 40°C to 60°C, and the drying time is 10h to 20h. The immersion time is preferably 12h, the drying temperature is preferably 40°C, and the drying time is preferably 12h.

[0024] Preferably, in S9, the calcination temperature is 680°C to 750°C, the calcination time is 3h to 6h, the etching solution is 2M NaOH alkaline solution, and the etching time is 10h to 16h. The calcination temperature is preferably 700°C, the calcination time is preferably 4h, and the etching time is preferably 12h.

[0025] Preferably, in S10, the drying temperature is 50° C. to 80° C., and the drying time is 10 h to 16 h. The drying temperature is preferably 60° C., and the drying time is preferably 12 h.

[0026] The advantages and positive effects of the hierarchical pore structure perovskite catalytic material and the preparation method thereof described in the present invention are:

[0027] 1. The present invention dopes the perovskite with the metal element Ca at the A position, which increases the surface active sites of the perovskite, distorts the unit cell structure, and changes the valence state of the lattice ions, thereby significantly improving the catalytic performance of the perovskite. 0.8 Ca 0.2 MnO 3 As the active center of the catalyst, Ca-doped perovskite is superior to conventional LaMnO 3 、LaCoO 3 and LaFeO 3 It has higher catalytic activity, more abundant oxygen vacancies, better structural stability and optimized ion mobility.

[0028] 2. The present invention uses silica microspheres as templates and orderly stacks materials by self-assembly, thereby constructing a three-dimensional ordered macroporous structure (3DOM). This modification method increases the specific surface area of ​​the catalyst to a certain extent and optimizes the pore structure of the material, thereby increasing the number of surface catalytic active sites and the mobility of oxygen species. At the same time, the application of silica microsphere templates avoids the problems of pore structure damage and cost increase caused by traditional organic polymer templates during template removal.

[0029] 3. The present invention also introduces surfactants to promote the formation of surface mesoporous pores, improve surface chemical properties and enhance the dispersibility of perovskite, forming a mesoporous structure on the three-dimensional ordered macroporous structure skeleton, so that the perovskite catalyst has both macroporous and mesoporous pore structures, which has the hierarchical advantage that a single pore structure does not have, reduces the mass transfer resistance inside the catalyst, and improves its contact efficiency with the reactants.

[0030] 4. The present invention etches the catalyst with an alkaline solution to enrich its surface functional groups and structural defects, thereby further improving the catalytic performance.

[0031] 5. The preparation method of the present invention is simple and low-cost, which is conducive to industrial production.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of an embodiment of the present invention;

[0034] Figure 2 XRD diagrams of the catalysts prepared in Example 1, Example 2, Example 7, and Comparative Example 1 of the present invention;

[0035] Figure 3 The microscopic morphology of silica microspheres and perovskites prepared in the present invention; (a) is a SEM image of ordered silica microspheres, (b) is a SEM image of Comparative Example 1, (c) is a SEM image of Example 1, (d) is a SEM image of Example 2, (e) is a SEM image of Example 7, and (f) is a TEM image of Example 7;

[0036] Figure 4 The methane conversion rate curves of the perovskite catalysts prepared in Examples 1-9 and Comparative Example 1 of the present invention;

[0037] Figure 5 is the H of the perovskite catalyst prepared in Example 2, Example 7 and Comparative Example 1 of the present invention. 2 -TPR test results. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0039] Example 1

[0040] A La 0.8 Sr 0.2 MnO 3 The preparation method of the perovskite catalyst material comprises the following steps:

[0041] (1) Weigh 0.012 mol of lanthanum nitrate, 0.003 mol of strontium nitrate, 0.015 mol of manganese nitrate and 0.03 mol of citric acid (a complexing agent) and dissolve them in deionized water. Place the solution in a magnetic stirrer at 65°C and stir continuously until it becomes a gel;

[0042] (2) The gel precursor was placed in a ventilated drying oven at 105°C for 12 h, and after coarse grinding, calcined at 800°C in air for 2 h to obtain La 0.8 Sr 0.2 MnO 3 Perovskite.

[0043] Example 2

[0044] This example adopts the method of Example 1 to prepare the perovskite catalyst La0.8 Ca 0.2 MnO 3 The only difference is that the added 0.003 mol strontium nitrate is replaced by 0.003 mol calcium nitrate.

[0045] Example 3

[0046] This example adopts the method of Example 1 to prepare the perovskite catalyst La 0.8 K 0.2 MnO 3 The only difference is that the added 0.003 mol strontium nitrate is replaced by 0.003 mol potassium nitrate.

[0047] Example 4

[0048] This example adopts the method of Example 1 to prepare the perovskite catalyst La 0.8 Ce 0.2 MnO 3 The only difference is that the added 0.003 mol strontium nitrate is replaced by 0.003 mol cerium nitrate.

[0049] Example 5

[0050] This example adopts the method of Example 1 to prepare the perovskite catalyst La 0.9 Ca 0.1 MnO 3 The difference is that the added 0.003 mol strontium nitrate is changed to 0.0015 mol calcium nitrate, and the added amount of lanthanum nitrate is 0.0135 mol.

[0051] Example 6

[0052] This example adopts the method of Example 1 to prepare the perovskite catalyst La 0.7 Ca 0.3 MnO 3 The difference is that the added 0.003 mol strontium nitrate is changed to 0.0045 mol calcium nitrate, and the added amount of lanthanum nitrate is 0.0105 mol.

[0053] Example 7

[0054] like Figure 1 This embodiment provides a preparation process of a Ca-doped hierarchical pore structure perovskite catalyst, comprising the following steps:

[0055] (1) 50 mL of ammonia water and 200 mL of ethanol were used to prepare solution A, and 200 mL of ethanol and 25 mL of tetraethyl orthosilicate were used to prepare solution B. Solution B was quickly dissolved in solution A while stirring continuously. The obtained mixed solution was placed in a 60° C. water bath and stirred for 4 h until the reaction was complete.

[0056] (2) Take the above mixed solution and carry out a 30-min centrifugation step at a speed of about 2000 rpm to filter out the white precipitate; repeatedly wash the precipitate with deionized water and ethanol to remove the residual reaction solution, and after the pH is reduced to 7, place it in a ventilated drying oven at 50°C for 12 hours to obtain pure silica microspheres. On this basis, weigh 1g of silica microspheres and pour it into 50mL of ethanol solution, ultrasonically oscillate for 1 hour, and centrifuge at 3000 rpm for 12 hours. Subsequently, filter the supernatant and dry the precipitate at room temperature for 48 hours to obtain a self-assembled ordered silica microsphere template material;

[0057] (3) According to La 0.8 Ca 0.2 MnO 3 According to the stoichiometric ratio, 0.012 mol, 0.003 mol, and 0.015 mol of lanthanum nitrate, calcium nitrate, and manganese nitrate were weighed and dissolved in 10 mL of deionized water to prepare a precursor solution. 3 mL of ethylene glycol solution was measured and slowly added to the precursor solution; then, 7.2 g of citric acid was weighed and added to the precursor solution, and stirred at room temperature for 4 hours;

[0058] (4) Weigh 2 g of ordered silica microspheres and add them to the above precursor, soak at room temperature for 12 h, then vacuum filter to obtain a wet mixture, and place it in a 40°C forced air drying oven for 12 h; place the dried mixture in a 700°C muffle furnace for calcination for 4 h, and etch the silica microspheres with a NaOH solution at 80°C for 12 h; then wash with deionized water to a pH of 7, and then place it in a ventilated drying oven at 60°C for 12 h to obtain EG-3DOM La 0.8 Ca 0.2 MnO 3 Perovskite catalysts.

[0059] Example 8

[0060] This example adopts the method of Example 7 to prepare the perovskite catalyst PEG-3DOM La 0.8 Ca 0.2 MnO 3 The only difference is that the added surfactant is polyethylene glycol, and the added amount is 3 mL.

[0061] Example 9

[0062] This example adopts the method of Example 7 to prepare the perovskite catalyst P123-3DOM La 0.8 Ca 0.2 MnO 3 The only difference is that the added surfactant is block polyether and the added amount is 3 mL.

[0063] Comparative Example 1

[0064] In this comparative example, LaMnO was prepared by the traditional sol-gel method. 3 The perovskite catalyst specifically comprises the following steps:

[0065] (1) Weigh 0.015 mol of lanthanum nitrate, 0.015 mol of manganese nitrate, and 0.06 mol of citric acid as a complexing agent and dissolve them in deionized water to prepare a precursor solution;

[0066] (2) The solution was evaporated to a gel state at 85°C under stirring conditions at a stirring speed of 600 r / min; then placed in a 130°C constant temperature drying oven for aging for 12 h, and the obtained precursor was calcined at 900°C in an air atmosphere for 4 h to obtain LaMnO 3 Perovskite powder.

[0067] Figure 2 The XRD patterns of the catalysts prepared in Example 1, Example 2, Example 7 and Comparative Example 1 of the present invention are shown in FIG. Figure 2 As shown, the characteristic diffraction peaks at 23.0°, 32.8°, 40.4°, 47.0°, 58.4° and 68.1° of all embodiments correspond to the perovskite phase (La 0.8 Ca 0.2 MnO 3 PDF#44-1040) of 020, 022, 040, 422, 404 and 206 lattice planes, indicating that the prepared catalyst has a good perovskite crystal phase. Compared with Comparative Example 1, the diffraction peak intensity of Examples 1 and 2 at 2θ=32.8° is enhanced, indicating that Sr and Ca element doping leads to improved perovskite crystallinity, and appropriate element doping is conducive to the formation of an ideal perovskite crystal structure. In addition, the diffraction peaks of Example 2 at other positions are reduced to a certain extent, proving that Ca element doping reduces the grain size of Example 2. No obvious characteristic peaks belonging to silica were found in the spectrum of Example 7, indicating that the microsphere template inside the catalyst has been completely removed during the alkali treatment process. In addition, at the position of 2θ=28°, a peak belonging to La(OH) 3 The characteristic peaks confirm that the alkaline solution etches the catalyst to enrich its surface functional groups and structural defects.

[0068] Figure 3The microscopic morphology of silica microspheres and perovskites prepared by the present invention; (a) is the SEM image of ordered silica microspheres, (b) is the SEM image of comparative example 1, (c) is the SEM image of example 1, (d) is the SEM image of example 2, (e) is the SEM image of example 7, and (f) is the TEM image of example 7. The average particle size of the silica microspheres is about 400nm, and they are closely arranged and stacked in layers with ideal orderliness. With the partial substitution of Sr and Ca elements at the A position, the particle size of the perovskite surface is reduced, and the agglomeration phenomenon is alleviated. In contrast, the La in Ca-doped Example 2 0.8 Ca 0.2 MnO 3 The catalyst showed the smallest particle size. In addition, the hierarchical pore structure design of the perovskite made the disordered state of the perovskite particles orderly, including orderly arranged macropores and mesopores distributed on the pore walls. 0.8 Ca 0.2 MnO 3 The macropores of the perovskite catalyst are closely arranged and interconnected, which is related to the close arrangement of the silica template. The precursor filling is weak at the contact between the microspheres, and there is a certain shrinkage during the calcination process, which leads to the formation of this structure.

[0069] The pore structure parameters of the perovskite catalysts prepared in Example 1, Example 2, Example 7, Example 5, and Comparative Example 1 are shown in Table 1. The total pore volume of Example 7 and Example 8 increased to 0.16 cm 3 / g, 0.15cm 3 / g, proving the existence of a three-dimensional ordered macroporous structure in perovskite. The specific surface area of ​​Example 7 is as high as 66.9 m 2 ·g -1 , indicating that compared with Comparative Example 1, Example 1, and Example 2, Example 7 has a larger specific surface area and more pore structures, which increases the number of surface catalytic active sites and the mobility of oxygen species. At the same time, the average pore size in Example 7 is 11.8nm, slightly larger than that in Example 8, indicating that ethylene glycol is conducive to the formation of surface macropores, while polyethylene glycol can promote the appearance of mesopores on macropores.

[0070] Table 1 Pore structure parameters of perovskite catalysts

[0071]

[0072] Figure 4 The methane conversion rate curve of the perovskite catalyst prepared in Examples 1-9 and Comparative Example 1 of the present invention, the temperature rise range is set to 300°C to 700°C, and the temperatures corresponding to T when the methane conversion rates are 10%, 50% and 90% are 10 、T 50 and T90 .like Figure 4 As shown, the methane catalytic activity of Examples 1, 2, 3 and 4 is better than that of Comparative Example 1 prepared by the traditional sol-gel method. This is due to the fact that the doping of Sr, Ca, K and Ce elements at the A position increases the surface active sites of the perovskite, distorts the unit cell structure and changes the valence state of the lattice ions, thereby improving the catalytic performance of the perovskite. Combined with the characterization results of XRD, SEM, TEM, etc., the Ca-doped perovskite has higher crystallinity and specific surface area, lower grain size and weaker surface particle agglomeration. This is because the atomic radius of Ca is larger than Ce, but smaller than Sr and K. Too high or too low atomic radius is not conducive to the formation of an ideal perovskite crystal structure. Similarly, among Examples 2, 5 and 6, Example 2 has a lower methane ignition temperature and complete combustion temperature, proving that by adjusting the doping amount of Ca element, the degree of perovskite lattice distortion can be improved, thereby affecting the catalytic activity, while too high or too low doping amounts are not conducive to improving the catalytic performance, and the threshold value of the doping amount is about 0.2. The conversion temperature of Example 7 is reduced most significantly, and its T 10 and T 90 The temperature dropped from 392.5 and 535.5°C to 374.3 and 509.4°C respectively. The reason for this significant decrease is that the hierarchical pore structure reduces the mass transfer resistance inside the catalyst, improves the contact efficiency between the reactants and the catalyst surface, and thus improves the overall catalytic efficiency of the perovskite. The above results all prove that the hierarchical pore structure perovskite in the present invention is an effective modification method for improving the catalytic activity of methane.

[0073] Figure 5 is the H of the perovskite catalyst prepared in Example 2, Example 7 and Comparative Example 1 of the present invention. 2 -TPR test results. Figure 5 As shown in Figure 2, the reduction peak of each sample at around 400 °C is attributed to Mn 4+ Reduction to Mn 3+ , while the reduction peak above 700℃ is attributed to Mn 3+ To Mn 2+ The main peak of the low-temperature reduction peak of Example 7 moves forward to 390°C, while the half-peak width of the secondary peak increases, indicating that the high-valent Mn species in Example 7 occupy a higher proportion and the low-temperature redox performance of the catalyst is improved, which is due to the doping of the A-site Ca element and the hierarchical pore structure.

[0074] Therefore, the use of the hierarchical pore structure perovskite catalytic material and the preparation method thereof described in the present invention can solve the problems of high cost and poor catalytic performance of existing catalysts.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A hierarchical pore structure perovskite catalytic material, characterized in that: The chemical formula is La (1-x) Ca x MnO3, where 0.1≤x≤0.3, there are two pore structures, macropores and mesopores, in the catalytic material.

2. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 1, characterized in that: The following steps are involved: S1. Prepare two solutions A and B, wherein solution A is an ethanol solution of ammonia water and solution B is an ethanol solution of tetraethyl orthosilicate; S2, mixing solution A and solution B, stirring evenly at room temperature, and then heating and stirring to obtain a suspension; S3, centrifugation filtration of the suspension to obtain a white precipitate, the centrifugal speed is 1000 rpm to 2000 rpm, and the centrifugal time is 20 min to 50 min; S4, washing the white precipitate with a deionized water solution of ethanol until the pH is neutral; drying to obtain a silica microsphere material, the drying temperature is 30°C to 80°C, and the drying time is 8h to 24h; S5, adding silica microspheres into an ethanol solution, and obtaining a self-assembled ordered silica microsphere template material after ultrasonication, centrifugation, filtration and drying; S6. Weigh lanthanum nitrate, manganese nitrate, and doped metal salt and dissolve them in deionized water to prepare a precursor solution; S7, adding a surfactant and citric acid to the precursor solution, stirring evenly at room temperature to obtain a mixed solution; S8, adding the self-assembled ordered silica microsphere template to the mixed solution of S7, fully impregnating, vacuum filtering, and drying in a forced air drying oven to obtain a solid mixture; S9, placing the solid mixture into a muffle furnace for calcination, and cooling to room temperature; etching with an etching solution at 60° C. to 90° C. to obtain a coarse-grade pore perovskite material; S10, washing the coarse-grade pore perovskite material with deionized water until it becomes neutral, and obtaining the fine-grade pore perovskite material after drying.

3. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In the S1, the volume ratio of ammonia water to ethanol in the A solution is 1:3-5; the volume ratio of tetraethyl orthosilicate to ethanol in the B solution is 1:6-9.

4. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In S2, the heating temperature for heating and stirring is 50°C to 70°C, and the stirring time is 3h to 4h.

5. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In the S5, the mass ratio of silica microspheres to ethanol solution is 1:40-60, the ultrasonic oscillation time is 0.5h-2h, the centrifugal speed is 2000rpm-3000rpm, the centrifugal time is 8h-16h, and the drying is carried out at room temperature for 24h-72h.

6. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In the S6, the doped metal salt is one of strontium nitrate, calcium nitrate, potassium nitrate and cerium nitrate, and the molar ratio of lanthanum nitrate, manganese nitrate and the doped metal salt is 3-5:4-6:

1.

7. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In S7, the surfactant is a mixture of one or more of ethylene glycol, polyethylene glycol, and block polyether, the mass ratio of the surfactant to citric acid is 1:2-4, and the stirring time at room temperature is 3h-6h.

8. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In the above S8, the immersion time is 10 h to 20 h, a hydrophilic polytetrafluoroethylene microporous filter membrane with a pore size of 0.45 um is used for suction filtration, the drying temperature is 40° C. to 60° C., and the drying time is 10 h to 20 h.

9. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In the S9, the calcination temperature is 680°C to 750°C, and the calcination time is 3h to 6h; the etching solution is a 2M NaOH alkaline solution, and the etching time is 10h to 16h.

10. The method for preparing a hierarchical pore structure perovskite catalytic material according to claim 2, characterized in that: In the step S10, the drying temperature is 50°C to 80°C, and the drying time is 10 hours to 16 hours.

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